Sydney FC have signed Socceroos defender Sasa Ognenovski until the end of the A-League season.

The Sky Blues confirmed the new deal for Ognenovski on Tuesday amid speculation the 34-year-old was on the verge of putting pen to paper.

Ognenovski left Qatari club Umm-Salal in December and was keen to return to Australia to help boost his chances of a World Cup call-up, having been axed from the national squad by new coach Ange Postecoglou before November's friendly against Costa Rica.

The centre-half is set to join his new teammates for training on Thursday and will be available for Saturday's home game against Adelaide United at Allianz Stadium.

"It is always good when you are wanted by a big club and Sydney FC are an iconic club in Australian football," Ognenovski said.

"It will be an honour to pull on the sky blue shirt.

"I'm looking forward to the challenge of playing back in the Hyundai A-League and I know the standard and the quality of the league."

Coach Frank Farina said Ognenovski's wealth of experience at international and club level would bring extra stability to his side's back four.

"He recently helped Australia qualify for the World Cup in Brazil and has also won the Asian Champions League and Asian Player of the Year, so we are bringing in real quality to back up what we already have in that position," Farina said.

"Sasa demands success and is the type of player and character we want at this club.

Meanwhile, Central Coast coach Phil Moss has declared it a landmark day for the A-League and his club after added Kim Seung-yong to his rapidly replenishing playing stocks.

The signings of Kim from Korean team Ulsan Hyundai and much-travelled central defender Eddy Bosnar have reversed the recent traffic flow out of the A-League champions following the departures of Daniel McBreen, Michael McGlinchey and Trent Sainsbury to clubs in China, Korea and the Netherlands respectively.

Moss is hopeful Kim and Bosnar will make their debuts against Melbourne Victory in Gosford on Saturday, although the pair are still awaiting international transfer clearance from their former clubs.

With midfielders Isaka Cernak and Glen Trefiro also poised to join the Mariners in the next couple of days, Moss believes the new arrivals will restore the competitive balance to a club that have lost several of their top performers over the past few months in addition to premiership-winning coach Graham Arnold to J-League outfit Vegalta Sendai.

"I think this is a landmark day for the A-League and definitely the Central Coast Mariners as well, to have a player of Kim's quality and standing in Asian football," Moss said.

Moss received glowing recommendations about his new Korean acquisition from Bosnar, striker Matt Simon and former Mariners skipper Alex Wilkinson, who have all faced him in the K-League.

"As soon as I saw the vision (of Kim) ... and then his playing CV, it was pretty much a no-brainer," Moss said.